Does the environment play a role in heart health?

Heart health, as a major contributor to wellness, is increasingly under threat from the insidious effects of air pollution. While heart disease is commonly associated with lifestyle choices (i.e., smoking, alcohol, diet, exercise), the role of environmental degradation – particularly air quality – is playing a more silent but nonetheless important role.

According to the World Health Organization (WHO), both short and long-term exposure to air pollution is responsible for the increased risk of respiratory infections, lung cancer, and heart disease.

The U.S. Environmental Protection Agency (EPA) pollution standards were designed to protect health. As a result, air quality has improved. The Clean Air Act has contributed to falling ozone, as well. However, pollution standards have become a moving target due to the evolution of climate change.

And health is feeling the impact. According to the American Lung Association’s 2023 State of the Air report, nearly 120 million Americans still live within areas occupied by unhealthy levels of ozone or particulate pollution. Air pollution is responsible for approximately seven million deaths annually around the world.

What are air pollutants?

Air pollutants are a mixture of hazardous substances, solid or gas, natural or synthetic, that when released into the air, indoors or outdoors, can be harmful to the health and wellness of a living being.

Particulate matter (PM), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3) are some of the most significant pollutants known to contribute negatively to health.

The cardiovascular consequences of air pollution

Cardiovascular disease, in particular, can be caused by pollutants triggering inflammation, oxidative stress, and endothelial dysfunction.

Inhalation of pollutants can contribute to chronic inflammation in the body, specifically within the blood vessels. Vessels that become inflamed are prone to plaque buildup. Hardening and narrowing of the arteries as a consequence of plaque is known as atherosclerosis. This condition increases an individual’s risk of heart attack and stroke.

Outdoor air pollution, in particular, has been shown to worsen existing cardiovascular conditions. Particle pollution, including fine particulate matter, are pollutants with diameters less than 2.5 µm or PM2.5. These specific inhalable particles are associated with oxidative stress in the body.

Normal metabolic processes create free radicals. When there is an excess of free radicals in the body due to either the body’s inability to rid itself of the intermediates or to repair itself from damage, the result is oxidative stress. As with direct inflammation, oxidative stress is also responsible for damaging blood vessels and promoting the formation of arterial plaques.

Inhalation of fine particulate matter has also been shown to affect the autonomic nervous system, which plays a role in the electrical conduction of the heart.  This is particularly of importance to those with a predisposition for cardiac arrhythmias.

Finally, air pollutants can weaken the inner lining of blood vessels causing endothelial dysfunction. The cascade of events associated with inhaling fine PM includes a change in blood vessel anatomy resulting in constriction, calcification, and formation of blood clots, all of which lead to inadequate vessel tone and blood flow. The consequences of impaired vascular function are contributing factors to chronic high blood pressure.

The EPA has reported exposure to increased concentrations of PM2.5 over a few hours to weeks can trigger cardiovascular disease-related heart attacks and death. Both short and long-term exposure to PM2.5  is notably more significant to those with a pre-existing history of myocardial infarction, rhythm disorders, stroke, and heart failure.

Heart health, beyond air pollution

Beyond air pollution, the environment is playing an even bigger role in heart health than you may think. Here are five key environmental factors that may be contributing to your heart health:

1. Food Environment

Local food environment plays an important role in heart failure mortality. Areas with limited fresh fruit and vegetables and an excess of fast food tend to have higher rates of cardiovascular disease. Reduced food access and socioeconomic deprivation are thought to contribute to adverse cardiovascular outcomes.

2. Green Space

Access to open space and parks has been shown to promote physical activity and reduce stress. Consequently, there is a notable improvement in blood pressure as well as a reduction in cardiovascular risk.

3. Climate Change

Extreme heat and severe weather patterns have been associated with increased cardiovascular disease. Heat stress has been linked with increased cardiac workload, hemoconcentration, inflammation, and autonomic dysfunction. In post-hurricane mortality data, heart disease represents a major cause of death.

4. Urban Design

The layout of urban areas can influence activity levels. Ideal planning includes a promotion of activity, in an open space, with a heat island effect and reduced noise pollution.

When activity is not encouraged, there is an associated increased risk of obesity and heart-related conditions.

5. Noise Pollution

Chronic exposure to traffic noise has been linked to an elevation in stress hormones as well as oxidative stress. The combination of the two leads to vascular dysfunction and high blood pressure, both of which are associated with an elevated risk of heart disease.